I. Field of the Invention
The present invention is directed generally to the field of sophisticated or "smart" large caliber projectile ammunition and, more particularly, to an improved electrical communication system which facilitates the transmission of pre-launch communication from the firing mission computer to update the program of the round.
II. Description of the Related Art
The evolution of large caliber ordnance generally has led to the development of increasingly sophisticated projectiles and firing systems. Rather than just being aimed at a potential target and fired for a pre-selected distance or upon impact, many current rounds contain highly sensitive target proximity detection devices which operate precision arming and detonating circuits. This allows, for example, a projectile warhead to be detonated at its closest proximity to a target of interest. In addition to electronic control and sensing improvements, the construction of the rounds themselves has produced vastly improved capabilities in terms of the lethality produced by a single round on a target.
Conventional large caliber ammunition of the class described, such as that fired by military tank cannons, are typically breech loaded from inside the tank and electrically activated and fired also from within the tank. The projectiles typically are connected by a conductor to a firing pin which connects a source of direct current (DC) voltage supplied to the base of the round cartridge at the primer button with a thermal battery located in the nose portion of the projectile which, in turn, generates the power to operate the projectile electronics. The projectile electronics utilize memory storage to operate the pre-programmed target acquisition or proximity system, and the arming and detonating devices in the shell during the flight of the shell. A primer circuit which ignites the primer which, in turn, ignites the main propellant charge to fire the round is energized sequentially by DC voltage of opposite polarity after the thermal battery is activated.
This is further illustrated in FIGS. 3A and 3B, and will be described in greater detail with reference to the round of FIG. 1 below. The entire system, then, has conventionally been activated utilizing a programmed direct current (DC) source such as that shown in FIG. 3A. In FIG. 3A, a source of direct current, which normally is the storage battery of the tank, is depicted at 11 as being connected to a fire control box 12 as, for example, by a polarity reversing double pole switch 13. The projectile contains a control electronics package 22, powered by a thermal battery 14a activated by an electric match depicted at 14 which is located in the forward portion or nose of the projectile. A primer 15 is attached to the fire circuit which includes bridge wire 16. The battery match 14 and the primer bridge wire 16 are connected in parallel to the source of DC voltage which is applied through the primer button 17 via conductors 18 and 19, respectively. Oppositely disposed diodes 20 and 21 operate in conjunction with the fire control box 12 and switch 13 to control the activation and firing sequence of the round. As shown in the waveform of FIG. 3B, the initial signal transmitted into the electrical system is a voltage having a negative polarity which, in turn, is blocked by the diode 21 and transmitted by the diode 20 thereby activating the thermal match 14 and the associated thermal battery system 14a which, in turn, activates the projectile electronics package 22. After a short duration, perhaps 5 msec, the voltage is returned to polarity zero for another short period of time, possibly 5 msec, and thereafter the voltage is reversed to a positive value which, in turn, is transmitted by diode 21 and blocked by diode 20 such that positive voltage is now pressed across the primer bridge wires 16 which are heated by resistance and burn through almost at once, thereby igniting a primer material which, in turn, ignites the main propellant charge, firing the projectile. In the interim, the thermal battery which was first activated has activated all the projectile electronics including any target acquisition or proximity sensing devices, together with the electronics associated with arming and detonating the shell. Of course, the conductor 18 is destroyed during the firing of the projectile, but it is of no further use once the thermal battery 14a is activated. The voltage waveform shown in FIG. 3B is generated by electronics in the fire control box 12 and switch 13 in a well-known manner and is utilized herein to described the presently known direct current method of arming and firing such projectiles.
With the typical DC system, it is much more difficult and, in some cases, not possible to change or update any preprogrammed information stored in the electronics package in the nose of the projectile. It would present a definite and desirable advance in the art if it were possible to communicate additional information to the projectile to update the memory just prior to launch. It would be convenient if this could be accomplished utilizing a data transmission system with high frequency carrier AC capabilities. This would allow the transmission of high frequency data to the sensor electronics, which would enable the tank crew to take full advantage of updated information with respect to the immediate situation and thereby enable them to more fully utilize the sophisticated capabilities of the projectile itself on a real-time basis.